1. Field of the Invention
The present invention relates generally to electrical protection devices, and particularly to electrical protection devices with environmental protection features.
2. Technical Background
As those of ordinary skill in the art will understand, an electric circuit comprises many different electrical wiring devices disposed at various locations throughout a structure. These devices include outlet receptacles, which may be combined with other wiring devices such as switches, lighting devices and protective wiring devices. Ground fault circuit interrupters (GFCIs), and arc fault circuit interrupters (AFCIs) are examples of protective devices in electric circuits. Each of the aforementioned protective devices have interrupting contacts for breaking the connection between the line terminals and load terminals when the protective device detects a fault condition. The connection is broken to interrupt the load current and thereby remove the fault condition.
Fault conditions include those that result in risk electrocution of personnel, or fire. The outlet receptacles are disposed in duplex receptacles, decorator receptacles, raceway, multiple outlet strips, power taps, extension cords, light fixtures, appliances, and the like. Outlet receptacles may be configured for installation in outlet boxes. Once installed, a faceplate may be attached to the cover of the outlet receptacle or to the junction box to complete the installation.
Most of these devices have line terminals for connection to the power line, and load terminals for connection to a load. The load terminals include receptacle contacts, feed-thru terminals, or both. The receptacle contacts are configured to accommodate the blades of a plug connector, which are inserted to provide power to a load. Feed-thru terminals, on the other hand, are configured to accommodate wires which are connected to one or more additional receptacles, known as downstream receptacles. The downstream receptacles may include a string of downstream receptacles that comprise part of a branch circuit of an electrical distribution system.
In many applications, users desire to install one or more of the aforementioned conventional wiring devices in an outdoor space, a garage, or some other space that may be exposed to dust, moisture, insects, and/or other contaminants. Unfortunately, conventional wiring devices are not equipped to repel such things. In the event that water is applied, whether by design or by accident, a live wiring device may become a shock hazard. Conventional wiring devices have other drawbacks. Even if the moisture level does not constitute a shock hazard, corrosion may develop over time. A conventional wiring device may also degrade in a dusty environment, or be compromised by insect infestation. A conventional protective wiring device includes sensitive circuitry that makes these devices particularly vulnerable to contaminants. Protective devices such as GFCIs are often installed in the most environmentally exposed areas. For example, GFCI protection is required for outdoor receptacles, bathrooms, kitchens, basements and garages. Finally, conventional wiring devices allow air to flow between the device and the interior of the wall box. Such air drafts may compromise the energy efficiency of the structure.
In one approach that has been considered, a gasket may be inserted between the wiring device and the wall plate after the installation of the wiring device. This approach has several drawbacks. Since the installation of the gasket is left to the installer, there is no guarantee that the gasket will match the shape and form factor of the installed wiring device. In addition, there is no guarantee that the installer will properly install the gasket. In either instance, the gasket will not perform in an ideal way.
In another approach, a wiring device having a gasket ultrasonically welded between a device cover and body member has been considered. However, this approach was also found to have several drawbacks. First, while the gasket does seal the receptacle hot, neutral and ground openings from some contaminants, it is not water tight and, therefore, the device is not completely effective against momentary exposure to water. Further, because it does not provide a draft seal around the perimeter of the wall box opening, air, water, insects and dust are able to penetrate the gap between the wiring device body, the interior wall of the device wall box, and the wall plate.
What is needed therefore, is an environmentally protected wiring device that may be disposed in outdoor, or environmentally exposed areas. A device is needed that provides a durable and effective shield against dust, water, insects and other contaminants. A wiring device is further needed that effectively seals the gap between the wiring device body, the interior wall of the device wall box, and the wall plate.